Hello, when playing a chord what does it mean when one of the notes has an x? What I'm specifically talking about is when the chord looks like this 7

Is the x just another way of saying to play it open?
It means don't play that string. An O is used to indicate playing the string open.
How can you tell a difference between this and a ghost note? From what I understand, an X is also used for a ghost note when you just simply place a finger on your left hand on the string without pressing it down. Sorry for the stupid questions haha.
It often means that you still pick the string but do not fret - thus muting the note. Good for scratchy sounds, crunchy rhythms, percussive playing and stuff.
But boys will be boys and girls have those eyes
that'll cut you to ribbons, sometimes
and all you can do is just wait by the moon
and bleed if it's what she says you ought to do